March of the Dead is a side quest in Skyrim: Dragonborn.
It is one of the two quests required in order to own a house in Raven Rock
How to Start
Approach Old Attius Farm
Attius Farm Clues
Captain Veleth explained that the Ash Spawn have been attacking Raven Rock for some time now, and he's been trying to locate their source. His lack of manpower and reluctance to leave the town without a commander are keeping him from finding out more. As a result of our conversation, I've agreed to help him deal with this situation. I need to begin by searching the Attius Farm for clues that might lead me to the Ash Spawn's source.
Captain Veleth was alarmed by the Strange Note I recovered from the Ash Spawn in Attius Farm. The note mentions Fort Frostmoth, the ruins of an imperial fort located southeast of Raven Rock. According to him, the fort's been abandoned ever sine the eruption of the Red Mountain. He's sent me to Fort Frostmoth to kill the author of the note, General Falx Carius, before the town falls prey to his threats.
As you approach Old Attius Farm to the East of Raven Rock you find some Ash Spawn attacking Captain Veleth. This begins the quest. Start by killing those Ash Spawn, then talk to Captain Veleth. He wants you to search the farm for clues. Loot the Ash Pile and find a Declaration of War. Talk to Veleth again and give him the note. He sends you to Fort Frostmoth to kill General Falx Carius. Inside the fort, you will have to do down until you find a Knapsack with the Fort Frostmoth Key key in it. Use the key to unlock the Wooden Door and enter quarters of General Falx Carius. Kill him, then return to Captain Veleth in Raven Rock